The various office automation equipments get more and more prevalent in modern life, the most common of which is the paper-breaker that servers for the paper breaking and thus the commercial confidence security. The paper-breaker has been used in family at present, the general paper-breaker is under the auto-inductive state when power-on or before the power-off, the paper-entry port is operated automatically if a certain object is to be detected and rolls in the object with a following breaking, in view of, however, the paper-breaker is a grind machinery with a certain danger related to its paper-breaking machinery part, the accident may be happened in case of carelessness operation, and the prior paper-breaker has no protection unit at the paper-entry port to protect foreign object and even human-body from enter into, should this occur, the paper-breaker may be damaged and even resulted with a human-body injury, it could not prevent the children or pets from operating the apparatus causally and thus bring about a safety problem for people.
A paper-breaker with human-body touch detecting function has been developed at present, refer to FIG. 1, each unit's function as follows:                •The SW2 is a polarity transfer switch, the live wire and ground line of electric supply power could be inter-changed with it.        •The resistor R12, R13, capacitors C3, C2, diodes D11, D12, D13, D14, D15, D6 constitute the relay power (24V) circuit.        •The diodes D6, D7 and capacitor C1 consist of the power circuit of the voltage detecting chip U1. Wherein, the positive pole of the power is the live wire of the electric supply.        •The relay switch RLY-1, diode D2, triode Q1, resistors R5, R27, R6 and optical coupler U5 constitute an apparatus operation power supply circuit.        •The diodes D1, D8, D21, temperature control indicating light (orange), triode Q4, resistors R4, R14, R11 and motor temperature control switch constitute a temperature control indicating circuit.        •The fuse F1, switch RLY1, motor, functional switch and motor temperature control switch constitute a motor operation circuit, the motor run direction corresponds to the functional switch position.        •The power, resistors R7, R1, R9, R2, R8, R10, diodes D20, D16, D4, D5, D9, D10, triodes Q2, Q3, fifth leg of the voltage detecting chip U1 constitute a LED light indication circuit.        •The panel metal part, resistors R20, R19, R21, R22, capacitor C8 and diodes D19, D17 constitute a touching detecting circuit.        
In case of the functional switch to be at the non-close position, the drum is separated from the apparatus, the magnetic-spring switch is turned off, the first leg of the voltage detecting chip U1 detects out a signal of the magnetic-spring switch off, the fifth leg of the voltage detecting chip U1 would turn out a high level, and the Q3, Q2 would be turned off. The Power indicating light, R7, touch indicating light, R8, D9 and motor temperature control switch from a loop. The power indicating light and touch indicating light would be switched on. The sixth leg of U1 turns out a high level at the same time, the triode doesn't work in cause of no base electrode positive voltage and the apparatus doesn't operate. In case of the drum is integral with the apparatus (i.e. the magnetic-spring switch is closed), the fifth leg of the U1 has a low level, the Q3, Q2 are on, the power indicating light is on, and the sixth leg of the U1 has a low level, the Q1 is on. The relay is closed. In case of the functional switch is at the reverse run position, the apparatus would run in reverse direction. In case of the functional switch is at the paper-breaking position, the apparatus would break the paper (paper entry signal is on), and the apparatus is in the stand-by state (paper entry signal is off). In case of the apparatus is in the operation state, if the hand, metal part or animal contacts with the metal part of the apparatus' upper cover, a loop would be formed through the human-body or metal via the R21, R19, R20 by the electric supply, the eighth leg of the U1 has a low level, and the fifth & sixth leg of U1 has a high level.                •In case of the sixth length of U1 has a high level, the Q1 would be off, the power is switched off, and the motor is stopped.        •In case of the fifth leg of U1 has a high level, the Q2 and Q3 are off, and the touch protective indicating light (orange) is on.        •When the hand, metal part or animal is separated from the metal part of the apparatus' upper cover, the apparatus would resume normal at once.        
In case of the functional switch is at the closed position, the apparatus doesn't work.
Owing to the fact that the conductive touch panel is installed at the paper-entry port of the paper-breaker, and the circuit is controlled by the conductance from human-body to the AC (electric supply) to achieve a touching protection purpose, and owing to the fact that electric supply is run through two 2.2MΩ resistors, the human-body-through current would be reduced without a human-body harm. The sensitive voltage detecting IC unit, however, be necessary to real-time monitor the state of the conductive touch panel, and the higher stability and sensitivity of the IC unit are thus needed, an elongated usage and aged circuit would result a weakened detecting function; although two large resistors are to be applied to limit the current, under the humidity condition, however, the resistors wouldn't have the protection ability, and the human-body may contact directly with the live wire of electric supply to result a shock or even danger to vitals.